Georgia Tech Team Reports Flaw In Critical Experiment on Fusion

By WILLIAM J. BROAD

Published: April 14, 1989

A critical experiment that was the strongest independent support for the claim that cold fusion had been achieved in a jar of water has turned out to be seriously flawed, researchers said yesterday at the Georgia Institute of Technology in Atlanta.

The news is sure to add confusion and controversy to an area of science that has already been thrown into turmoil by surprising claims. Also yesterday, University of Washington students reported that they had reproduced some of the disputed work.

At Georgia Tech, however, a scientific instrument that was used to measure neutrons, a key byproduct of nuclear fusion, apparently gave inflated readings because the liquid it was measuring became as hot as 120 degrees Fahrenheit.

''We're concerned about an apparent temperature dependence of the neutron probe we are using,'' Dr. James Mahaffey, leader of the Georgia Tech group of researchers, said in a statement. ''We are doing further experiments to clarify the impact of this temperature dependence. We will be releasing further information when we have it available.'' Flawed Probe Cited

John Toon, a spokesman at Georgia Tech, said that the flawed instrument was a probe that was apparently affected ''pretty dramatically by temperature. It may have been giving false readings, showing more neutrons than there really were. He said researchers were now struggling to reproduce their earlier work.

The original Georgia Tech work, announced on Monday, had been seen as lending strong support to a recent claim by scientists in Utah that they had achieved nuclear fusion in a jar of water. Of the hundreds of groups around the country that have been struggling to repeat the Utah experiment, to date only Georgia Tech and Texas A&M University had claimed results that appeared to have substantially strengthened the assertion by researchers at the University of Utah.

Of the two, the Georgia Tech results were considered stronger since it measured neutrons. The Texas A&M work measured only rises in heat, and its researchers said they were unsure whether fusion had actually occurred.

In a statement released Monday, Dr. Mahaffey said: ''The scientific and engineering prospects are limitless right now. It's like being there when fire was discovered.'' Doubts on Experiment

Mr. Toon said that doubts were first raised about the experiment yesterday afternoon when Dr. Mahaffey and his team of researchers were going over their results with scientists in other laboratories around the country, including Government ones. They said questions were raised about the temperature dependence of the probe, and they quickly proved to be serious.

Mr. Toon added that the Georgia Tech researchers were not yet sure whether the problem was with the individual probe, or was a more generic one.

''Really nobody had seen that kind of thing before,'' he said. ''We don't know if it's our equipment or inherent in the technology. We're trying to find out to what extent the neutron reading is attributed to the instrument error.''

The statement released by Dr. Mahaffey said that ''this temperature dependence was unexpected by both us and the manufacturer, and apparently has not been observed before.''

Unlike fission, in which atoms are split to produce energy in such devices as nuclear reactors, fusion involves the joining of the nuclei of hydrogen atoms to produce helium and large amounts of energy. Scientists have long sought unsuccessfully to produce controlled fusion reactions that might provide a cheap, nearly inexhaustible source of energy. Other Results Reported

Adding to the confusion, two graduate students at the University of Washington said yesterday that they had tentatively repeated the Utah experiment.

The two graduate students, Van L. Eden, 28 years old, and Wei Liu, 27, said they did the experiment with heavy water, as the University of Utah researchers suggested, and then with regular water for comparison purposes. They said that when the experiment was done with heavy water they appeared to detect tritium, a common radioactive byproduct of atomic fusion.

Each time regular water was substituted, Mr. Eden said, the signal for the presence of tritium went away.

As for whether a nuclear reaction had taken place, Mr. Eden said in an interview, ''We've got a signal that looks right, although it might be other things. We're trying to confirm it.'' The signal at the University of Washington indicating the possible presence of tritium was made on a mass spectrometer, which measures the atomic weights of nuclear particles. Mr. Eden said he and his colleague had been conducting the experiment for at least 10 days, alternately using water and ''heavy water,'' which is water made with deuterium, an isotope of hydrogen.